With the development of electronic communication technologies, electronic devices having various functions have been widely used. Such electronic devices generally have a convergence function for complexly performing one or more functions.
These electronic devices, including mobile terminals called ‘smart phones’ and wearable electronic devices to be worn on human bodies, have been made lighter, slimmer, shorter, and smaller, and at the same time have more functions to meet consumers' purchasing needs.
Currently, as the functional gap between electronic devices has decreased, electronic device makers have made efforts to increase the strength of the electronic devices, which have been made slimmer, and to improve design in order to meet consumers' purchasing needs. Reflecting this trend, constituent elements (e.g., external appearance) of electronic devices have been made of metal in order to increase strength and to achieve high quality and appealing external appearance of the electronic devices. In addition, efforts have been made to address the issue of grounding, degradation in antenna radiation performance, deficiency in mounting space for an antenna device, and the like, which have been caused by the use of metal.
In general, antenna radiation performance may be significantly degraded if a metal case is used in a situation where the thickness of an electronic device decreases in terms of design and a mounting space for an antenna radiator is insufficient. For example, if metal components or metal inner/outer mechanical parts exist around an antenna radiator, the capability of the antenna radiator may be considerably deteriorated by several phenomena, such as a scattering effect, an electromagnetic field trapping effect, mismatch, and the like, which are caused by metal. An electronic device of the related art has a sufficient space for mounting an antenna radiator and a sufficient separation distance from metal, and a dielectric material, such as plastic, is used as an exterior material of the product, so there is no difficulty in manufacturing an antenna radiator. However, since a currently used portable electronic device is made smaller and slimmer in order to raise consumers' purchasing needs and more frequently uses metal exterior parts, the separation distances between an antenna radiator and metal components and mechanical parts gradually decrease so that it is difficult to obtain sufficient performance using an existing antenna technology.
Among technologies of the related art for addressing such issues, the first method may have a limit on design due to the separation distance between metal and an antenna radiator. The lowermost end portion of a terminal is not formed of metal, and injection molding is applied to a certain portion that is used as a radiation space of the antenna.
The second method has to tune an unspecified slot corresponding to a frequency using the wide area of an adjacent battery cover when the battery cover is formed of metal. In this method, the tuning has to be performed many times in order to guarantee performance, so there is difficulty in determining the shape of a slot of the battery cover. Although an antenna is implemented by applying a slot to the metal battery cover, it takes a lot of time to tune the slot in order to apply the slot to an actual model, and a different model from the initial design concept may be made according to the shape of the slot.
The third method may cause a cost increase due to excess deflection of a mechanical part and added material in the process of connecting metal and an antenna, and the thickness of an electronic device may be increased due to an added component.
In the fourth method, an antenna structure (PIFA) that uses the ground as a radiator has drawbacks. For example, it has been known that since the ground is used as the radiator, the antenna characteristic may be easily changed by the human body, and an antenna gain is lowered by 6 dB or more by a person's hand. The major drawback of this method is that a variation in a current flowing in the ground may change the resonant frequency and bandwidth of the antenna.
Therefore, a need exists for an antenna device implemented to prevent the deterioration in radiation performance due to a metal mechanical part (e.g., a metal housing, a metal bezel, and the like), and an electronic device including the same.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.